1.打印1-100之间所有奇数之和

<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>Document</title>
    <script>
        var sum=0;
        for(var i=0;i<=100;i++){
            if(i%2!=0){
                sum+=i
            }
        }
        alert(sum)
    </script>
</head>
<body>
    
</body>
</html>

123.png

2.打印1-100之间所有7的倍数的个数及总和

<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>Document</title>
    <script>
        var sum=0;
        var list=[];
        for(var i=0;i<=100;i++){
            if(i%7==0){
                list.push(i)
                sum+=i
            }
        }
        alert(sum);
        alert(list.length);
    </script>
</head>
<body>
    
</body>
</html>

QQ图片20180918093131.png

QQ图片20180918093140.png

3.水仙花数是指一个3位数，它的每个位上的数字的3 次幂之和等于它本身。

<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>Document</title>
    <script>
        /*var a,b,c ;*/
        for(i=100;i<1000;i++){
            var a = parseInt(i%10);
            var b = parseInt((i/10)%10);
            var c = parseInt(i/100);
            if(a*a*a+b*b*b+c*c*c== i){
            alert(i  +"是水仙花数");
        }
        }
    </script>
</head>
<body>
    
</body>
</html>

水仙花.png

4.在页面中接收一个用户输入的数字，并判断该数是否是质数。

<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>Document</title>
    <script>
        var num=parseInt(prompt("用户输入的数字"))
        for (var i = 2; i < num; i++) {
            if (num%i==0){
                alert("不是质数");
                break;
            }else{
                alert("是质数");
                break;
            }
        }
    </script>
</head>
<body>
    
</body>
</html>

5.打印出1-100之间所有的质数

<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>Document</title>
    <script>
        for(i=2; i<=100; i++){
            for(var j=2 ; j<i ; j++){
                if(i%j == 0){
                    document.write(i+"<br/>");
                    break;
                }
            }
        }
    </script>
</head>
<body>
    
</body>
</html>

Document.png

6.打印99乘法表

<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>Document</title>
    <script>
        for(i=1;i<=9;i++){
            for(j=1;j<=9;j++){
            document.write (i+"*"+j+"="+i*j+"&nbsp&nbsp");
            if(i==j){
                    document.write ("<br/>");
                    break;
                }
            }
        }
    </script>
</head>
<body>
    
</body>
</html>

99.png